Improvement in quadruplex telegraphs



G. B. PRESCOTT.

QUADRUPLEX TELEGRAPH.

No. 190,898. Patented May15, 1877.

lllllhiiiiii KEYS AN D BA TTERY.

INVENTOR.

WITNESSES "THERE. PNOTO-LITHOGHAPNER. WASHINGTON, D c.

" NITED STATEs PATENT OFFICE.

GEORGE B. PRESCOTT, OF NEW YORK, N. Y.

IMPROVEMENT IN QUADRUPLEX TELEGRAPHS.

Specification forming part of Letters Patent No. 190,898, dated May 15,1877 application filed April 22, 1876.

To all whom it may concern Be it known that I, GEORGE B. PRESCOTT, ofthe city of New York, in the county and State of New York, have inventedcertain new and useful Improvements in Quadruplex Telegraphs; and I dohereby declare 'that the following is a full, clear, and exactdescription thereof, which will enable others skilled in the art towhich it appertains to make and use the same, reference being had to theaccompanying drawings, and to the letters of reference marked thereon,which form a part of this specification.

My invention relates to that class of quadruplex telegraphs in which tworeceiving-instruments are employed at each terminal station, one beingoperated by changes in the polarity of the line-current withoutreference to its strength, and the other by changes in the strength ofthe current without reference to its polarity.

My improvement consists in the peculiar construction and arrangement ofa differential receiving-instrument, operated by changes in the strengthof the current, in combination with a condenser, which is charged anddischarged by the current traversing the bridgewire, by means of whichcombination the mutilation of the signals upon this instrument,resulting from the reversal of the polarity of the line-current, whichhas hitherto formed a serious obstacle in working longlines, is moreeffectually prevented.

In the accompanying drawing, P represents a polarized relay or receivinginstrument, which is operated solely by changes in the polarity of thecurrent, and It represents a neutral relay, which is operated solely bychanges in the strength of the current. In some instances this relay isalso provided with a polarized armature. The main magnet of thereceiving-instrument B is provided with two equal and opposing helices,m 'n, preferably arranged in the manner shown in the drawing, althoughthe precise arrangement is not very material. The rheostats orresistances A and B, which form the first and second sides of thebridge, are preferably made equal to each other, and this being the casethe resistance X should, of course, be made equal to the resistance ofthe line. When the respective resistances are thus arranged thebridge-wire 3 5, polarized receiving-instrument P, and condenser G willbe in a neutral position in respect to outgoing currents.

The receiving instrument R is provided with an auxiliary magnet, T,which acts upon the same armature-lever with the main magnet m n. Thisauxiliary magnet is inserted in a wire. 7, which is connected to thebridgewire 3 5, and through which the condenserO is charged anddischarged. The charging and discharging of the condenser is effected asusual, by means of a rheostat, D, placed in the bridge-wire between thepoint of junction of the Wire 7 and that of the Wire 8, which isattached to the opposite pole of the condenser.

The outgoing currents, without regard to their strength or polarity,pass over the wire 1 to the point 2, where they divide into two equalportions, one portion going to line by way of A, 3, m, and 4, and theother to earth by way of B, 5, n, X, and 6. The bridge-wire 3 5, beingneutral in respect to outgoing currents, the instrument P will not beaffected, nor will the instrument R, for the reason that the currentstraversing the opposing helices m n are necessarily equal to each other.

For the purposes of this explanation it is only necessary to take intoconsideration the effects of such incoming currents as are of sufficientstrength to actuate the receiving instrument R. In my arrangement thefull strength of the incoming current, whatever may be its polarity,passes, unopposed, through the helix m of the instrument R, and thenceto the point 3, where it divides, one portion going to earth by way ofA, 2, and 1, another portion by way of 5, B, 2, and 1, and the remainderby way of 5 through the other coil 12 of the receiving-instrument R,(its direction now being such as to assist the action of the other helixm,) and thence through the rheostat X to the earth. The incoming currenttraversing the bridge-wire from 3 to 5, being partially obstructed bythe rheostat D, a portion of it flows through the wire 7 and charges thecondenser G.

If, now, the polarity of the current upon the line be suddenly reversedfor the purpose of operating the polarized receiving-instrument P, thearmature of the instrument It tends to fall off momentarily while thechange of polarity is taking place, but this action is prevented by thedischarge of the condenser G through the wire 7, which occurs at thesame instant, and, acting upon the auxiliary magnet r, retains thearmature-lever a in its place.

I am aware that it is not new to place a receiving-instrument, operatedby changes in the strength of current in the bridge-wire, in combinationwith an auxiliary magnet, a condenser, and a rheostat; nor is it new tomake use of a differential magnet placed in the circuit of the main andartificial line, instead of in the bridge-wire, in combination withanother receiving-instrument placed in the bridge-wire. I believe it,however, to be both new and important to substitute a differentialreceiving-instrument in the circuit of both the main and artificiallines for the receiving-instrument heretofore placed in the bridge-wire,and to combine therewith an auxiliary magnet actuated by the charge ordischarge of a condenser connected to the bridge-wire, as I am therebyenabled to util ize the entire strength of the incoming current, andobtain at least double the effective working margin from a givenstrength of current passing over the line, without sacrificing any ofthe advantages heretofore derived from placing this portion of theapparatus in the bridge-wire. By the use of my improvement it,therefore, becomes possible to work the quadruplex apparatus over linesof greater length than has hitherto been the case.

I claim as my invention- 1. A receiving-instrument composed of adifl'erential magnet whose opposing coils are respectively included inthe circuit of the main and of the artificial line, in combination withan auxiliary magnet, so arranged as to be operated by the charge ordischarge of a condenser.

2. A receiving-instrument provided with two electro-magnets acting uponthe same armature-lever, one a differential magnet, whose opposing coilsare respectively included in the circuit of the main and of theartificial line, and the other so arranged as to be actuated by thecharge or discharge of a condenser, in combination with a rheostatinserted in the bridge-wire, to effect the charging of said condenser,substantially as and for the purpose herein specified.

In testimony that I claim the foregoing I have hereunto affixed mysignature in the presence of two witnesses.

GEORGE BARTLETT PRESCOTT.

Witnesses:

H. M. HAIGH, E. W. GRIFFITH.

